1. Technical Field
The present invention relates to an image forming apparatus and an intermediate transfer member.
2. Related Art
Image forming apparatus in which a color image is formed by using an intermediate transfer member such as an intermediate transfer belt to electrostatically transfer toner are well known. When an image is formed on a sheet of paper using such an intermediate transfer member, four color images in yellow, magenta, cyan and black respectively are generally first transferred sequentially from an image carrier such as a photoreceptor and superimposed on the intermediate transfer member (the primary transfer), and this full color image is then transferred to a sheet of paper in a single step (the secondary transfer).
The types of paper that can be used within these image forming apparatus vary considerably, from paper with a smooth surface through to so-called embossed paper that includes unevenness within the paper surface. With uneven papers, a gap develops between the paper and the surface of the intermediate transfer member at indentations within the paper, and electrical discharge causes the toner formed on the surface of the intermediate transfer member to develop an inverse charge, which may result in unsatisfactory transfer. Particularly in systems that employ an intermediate transfer member, the toner that has been previously transferred by the primary transfer process gradually accumulates more charge as a result of transfer field effects and electrical discharge, meaning a large electric field is then required in the secondary transfer process to transfer this highly charged toner, and this may also exacerbate transfer problems to uneven papers.
In order to achieve a favorable transfer to an uneven paper with no transfer irregularities, the gaps that develop between the paper and the surface of the intermediate transfer member at the indentations within the paper should be eliminated as far as possible.